Oscillograph system



Aug. 10, 1937. c. s. RoYs ET A1.

OSCILLOGBAPH SYSTEM Filed Oct. 3, 1955 2 Sheets-Sheet 1 hmm. w

mvo.

Aug. 1o, 1937.

C. S. ROYS El' AL OSCILLOGRAPH SYSTEM Filed Oct. 3, 1955 2 Sheets-Sheet 2 Patented Aug. l0, 1937 UNITED STATES PATENT OFFICE OSCILLOGRAPH SYSTEM Application October 3, 1935, Serial No. 43,460

30 Claims.

I'his invention relates to oscillograph systems and has particular relation to novel systems of operation of cathode ray oscillographs.

As is now well known in the art, the cathode ray oscillograph is ideally suited for the observation of electrical phenomena, particularly because the amount of signal power consumed thereby is negligible, the frequency characteristic is perfectly flat from zero to frequencies far into the radio frequency range, the electron beam may ordinarily be considered as inertialess, and there are no moving parts to wear or to get out of adjustment. Modern cathode ray tubes may reasonably be expected to have a life of several thousand hours of operation, and the auxiliary apparatus required is likewise of long life and dependable nature.

Heretofore, however, the cathode ray oscillograph has not been considered well suited for the simultaneous observation of two or more electrical phenomena, such, for example, as the voltage impressed upon a circuit and the current flowing therethrough, Whereas other types of oscillographs, such as galvanometer and vibrat- 2,. ing mirror types, may be readily built to accommodate the observation of a plurality of characteristics of a circuit, or of different circuits, at

the same time.

The object of the present invention is to pro- 30 vide a system for controlling the operation of a cathode ray oscillograph whereby the same may be used for the simultaneous observation of a plurality of phenomena in their true mutual relationships.

The invention will be better understood and further objects and advantages thereof will become apparent from a consideration of the detailed description appearing hereinafter, taken in conjunction with the accompanying draw- 40 ings forming a part hereof, in which:

Figure l is a diagrammatic representation of a cathode ray oscillograph system constituting one embodiment of the invention;

Fig. 2 is a diagrammatic representation ofy a 45 modification of one portion of the system illustrated in Fig. 1;

Fig. 3 is a diagrammatic representation of a further modification of the same portion of the system; and

Fig. 4 is a diagrammatic representation of another modification of the same portion of the system, whereby the observation of additional phenomena may be accomplished.

Referring first to Fig. 1 of the drawings, the 55 system therein disclosed comprises a cathode ray (ci. 1v1-95) tube designated generally by the reference character Il and embodying an evacuated or gasllled envelope ordinarily made from a glass ask, the enlarged end of which is internally coated, as indicated at I la, with a screen material which 5 becomes fluorescent at a point where a high velocity beam of electrons strikes it. The source of the electron beam is a heated filament IIb near the opposite end of the fiask. The electrons are given a high velocity by impressing a high direct cur- 10 rent potential between one or more auxiliary electrodes, such as the electrode indicated at I Ic, and the cathode IIb. The electrons are then focused into a beam by an auxiliary electrode or electrodes such as that indicated at Hd. 15

The focused beam is then directed between two pairs of deecting plates Ile and Hf, which are set at right angles to each other. 'I'he deecting plates of each pair are subjected 'to differences of potential and the electron beam is 'thereby 20 deflected from the straight course which it would otherwise follow. Application of a potential between the two plates of one pair will deflect the beam toward the more positive plate. The potential applied between the two plates of the pair Ile, commonly called the X plates, produces a horizontal deflection of the beam, and such potential may be varied to produce a linear time axis on the screen Ila. The potential between the plates of the pair IIf, commonly called the Y plates, is varied in accordance with the quantity or phenomenon to be observed and produces a vertical deflection of the beam so that the variations of the quantity in question may be observed with relation to the predetermined time axis provided by the horizontal deection of the beam under the influence of the X plates Ile.

The oscillograph tube II further preferably comprises a conducting coating Hg over most of the interior surface of the tube between the defleeting plates and the screen IIa, and this conducting coating is so electrically connected with respect to the other elements of the electric circuit system, which Will be described hereinafter, as to prevent the building up of a static charge of electrons on that surface, with deleterious effects upon the operation of the device.

It will be understood that the design of the tube II is not essential to the operation of the systems embodying the present invention, and that the specific construction described above is simply one example of a suitable tube design.

The oscillograph tube I I is controlled by the system illustrated so that it serves for the simultaneous observation of two electrical quantities,

one 'of which is represented by a dierence of potential applied between terminals I2 and I3 and the other of which is represented by a difference of potential applied between terminals I4 and I5. It will be understood, of course, that the external connections of these terminals may be such as to provide for the observation of two characteristics vof, -.asingle circuit, such, for example, as the voltage and currentthe'reof, o'r that the connections may be made to diierent circuits for the purpose of simultaneous observation or comparison of predetermined characteristics thereof.

The internal connections between theterminals. I2 and I3 consist of insulating condensers |,6 and I1, a variable resistor I8, and a'potentiometer I9, all of which elements are connected in series between said terminals. The connections between the terminals I4 and I5 similarly comprise insulating condensers 20 and 2|, a variable resistor 22 and a potentiometer 23, all connected in series between said terminals. One end-of each of the potentiometers I9- and 23 is connected to one branch f a common conductor 24, which is preferably connected to ground, as shown at 25a, and which comprises several other branches having other elements of the system connected thereto.

The variable contacts of the potentiometers I5 and 23 are respectively connected to the grids of two triode amplifiers 25 and 26, such as type 56 triodes. The triode 25 comprises the first step of a two-stage amplifier for the quantity or signal impressed upon the terminals I2 and I3 and the second stage of said amplifier comprises a similar triode 21. The triode 25 similarly comprises the first stage of an amplifier for the signals connected to the terminals it and l5 and the second stage of the latter amplifier comprises another similar triode 23.

'I'he rst-stage amplifiers 25 and 26 are automatically biased by resistors 29 and 36, respectively, which are by-passed by condensers 3| and 32, these elements connecting the cathodes of the tubes 25 and 26 to the common ground conductor 24. The amplifiers of the first stage are coupled to those of the second stage by means of transformers 33 and 3G, the primary windings of which are lconnected between the plates of the tubes 25 and 26 and a suitable plate voltage source, hereinafter described, through resistors 35 and 36. The secondary windings of the transformers 33 and 34 are preferably loaded with resistors 31 and 38, respectively, and a doublepole, double-throw reversing switch 39 is connected between the secondary of the transformer 33 and the associated loading resistor 31 to provide for 180 shifting of the phase relationship between the two signal observations.

The transformers 33 arid 34 may suitably consist of audio transformers connected in stepdown relationship, the loading resistors 31 and 38 being utilized to give them a sufliciently iiat frequency characteristic. It will be understood, however, that any suitably designed transformers may be used and that the design may be such as to eliminate the necessity of using the loading resistors. In that case the transformers may very well have a 1:1 ratio.

Resistors. 35 and 36, in conjunction with bypass condensers 40, 4|, and 42, prevent any signal currents from flowing in the high-voltage supply circuit which might possibly cause regeneration or degeneration in the amplifier, and at the same time provide additional filtering for the -their grids.

vbetween the ground conductor 26 and the variyable contact of a potentiometer 51, the outside terminals of which are respectively connected to .the cathodes of the tubes 21 and 26. This potentiometer permits adjustment of the bias on the `two tubes to compensate for any slight differences in their characteristics, for it is necessary that each tubedraw exactly the same plate current in order for the two signals to be reproduced by the oscillograph on the same axis.

The filaments of the tubes 25, 26, 21, and 28 are `all connected in parallel across a, filament supply circuit comprising conductors 48 and 49, which extend to a suitable current source, hereinafter described. A mid-tap resistor comprising arms 5|) and 5| is connected between the two filament supply conductors, and the mid-point tap thereof is connected to the ground conductor 24 in order to reduce interference and distortion resulting from the use of alternating current for the filament supply.

A connection extends from the plates of the ampliers 21 and 28 through a blocking condenser 52 and a conductor 53 to one of the Y plates Ilf of the cathode ray tube, the other of said Y plates being connected to the ground conductor 213, all as described in detail hereinafter.

A connection extends from the plate of the first-stage amplier 26 through a conductor 56 to another portion of the system which will also be described hereinafter.

The grids of the second-stage amplifiers 21 and 28 are not connected to ground, as they ordinarily would be, but,- instead, are connected (through the secondary windings of transformers 33 and 34 and also through resistors 31 and 38, respectively associated therewith) to points 55 and 56 in a portion of the system which will be referred to as the commutating circuit. The action of the commutating circuit is such that points 55 and 56 are alternately at ground potential and at a potential which is negative with respect to ground, preferably to the extent of about 60 volts; that is to say, when the point 55 is at ground potential the point 56 is at a potential of about 60 volts negative with respect to ground, and vice versa. The result of this arrangement is that when" the point 55 is at ground potential the ampliflei` 21, which has its grid connected to said point 55 through the secondary winding of transformer 33, will have the normal bias provided by the connection through the resistor 45 and will amplify its signal and communicate it to the Y plates of the oscillograph II through the conductor 53. At the same time, the amplifier 28, having its grid connected to the point 56 through the secondary winding of transformer 34, will have an extra negative bias of, say, 60 volts, which is sufiicient to cut olf the plate current in the tube so that no signal can pass therethrough. When the commutating circuit operates to reverse the potential relationshipl of the points 55 and 56, the situation is reversed, so that the rst signal is blocked and the second one passed.

The commutating circuit comprises two gridprimary winding liasa manually-operable switch controlledrectifiers 51and58.suchaswpe885 gastriodeawhicharem acircular similar to the common single phase, two-tube inverter circuit. A manually-operable switch 5l is connectedbetweenthepointandthe platen! the triode 51, and a switch 8|) is similarly connected between the point 56 and the plate of the triode 58, these switches being normally closed. The operation of the triodes is controlled by another portion of the system known as the sweep circuit, hereinafter described, which is connected to the commutating circuit through a conductor 6|. This conductor is connected to one terminal of the primary winding 62 of an air-core transformer, the other terminal of which is connected to the ground conductor 24. This transformer 63 connected in shunt relationship thereto. This switch is normally open, but may be closed upon occasion to short-circuit the transformer primary winding and thereby to render the commutating circuit inoperative if it is desired to use the oscillograph for the observation of a single wave. The secondary winding 64 of the air-core transformer has one of its terminals connected to the ground conductor 24 and the other terminal thereof connected through condensers 65 and 66,

respectively, to the grids of the triodes 51 and 58.'

The grids of the triodes 51 and 58 are connected through resistors 61 and 68, respectively, to a conductor 69, which extends to the negative side of a source of direct current potential hereinafter referred to. The said source is the same as the one having its positive side connected to the conductor 43. The negative side of said source is `also connected through the conductor 69 and a.

variable resistor 1|] to the cathodes of both triodes 51 and 58. The laments of said triodes are connected in parallel across a suitable source of lament current, hereinafter described, by means of conductors 1| and 12. The points 55 and 56 in the plate circuits of the triodes 51 and 58 are connected to ground through resistors 13 and 14, respectively, and are also connected together by a condenser which shunts said resistors.

The sweep circuit above mentioned serves to control the horizontal movement of the electron beam in the oscillograph tube to provide a time axis for the observations to be made. This operation is accomplished by applying to the X plates ||e of the cathode ray tube a difference of potential which varies according to a predetermined cycle. At the start of the cycle, the dierence of potential is such as to cause the electron beam to impinge upon the screen I la at the zero point, and such difference of potential may be zero. The potential difference is then built up at a constant rate to a definite value which eects the maximum desired horizontal deflection of the beam away from the zero or starting point, and is then rapidly reduced to its initial value so that the beam returns with corresponding rapidity to the zero or starting point thereof.

The difference of potential which increases at a constant rate as above described is secured by means of a condenser 16 in the sweep circuit and a pentode 11 connected in series with said condenser across a direct current source of relatively high and constant voltage. The pentode 11, which may suitably consist of a type 57 tube, has an extremely high A. C. plate resistance so that changes in plate voltage have almost no eiect upon the plate current. The pentode therefore serves as a constant current device in the charging circuit of the condenser 16 and thus causes laid to be charged at essentially a constunt rate.

The X plates He of the oscillograph are connected directly across the condenser 16 by means of a connection from one terminal of said condenser to the ground conductor 24, to which one of the plates Ile is also connected, and by means of a conductor 19 extending from the other terminal of said condenser to the other one of the plates Ile. Additional condensers 80 and 8| are selectively connectible in parallel with the condenser 16 by means of a switch 82 so that different charging rates may be provided. An increase in the capacity of the condenser bank will cause the voltage thereacross to build up at a lower rate and will accordingly decrease therate Vat which n ,Y

the/electron beam'is'lnoved across the screen of the oscillograph. and vice versa.

As shown, the connections of the pentode 11 include a connection from the plate thereof to those terminals of the condensers 16, 88, and 8| which are connected to the conductor 18. The cathode of the pentode is connected to one terminal of a potentiometer 83, the other ter- Y minal of which is connected.through a series resistor 8 4 to the ground conductor 24 and the adjustable contact of which is connected to a conductor 85. The function of the resistor 84 is to compensate for the change in current consumption of the sweep circuit when the setting of the potentiometer 83 is changed, thus improving the voltage regulation.

As will appear hereinafter, the ground conductor 24 is connected to the positive side of a source of relatively high direct current potential, while the conductor 85 is connected to the negative side of said source. The control grid of the pentode is connected directly to the conductor 85 so that its bias is controllable by means of the potentiometer 83 and the screen of the pentode is connected to the adjustable contact of a potentiometer 86, whereby its voltage may be controlled, said potentiometer having its terminals connected 'to the conductors 24 and 85, respectively. The filament of the pentode 11 is connected to a suitable source of filament current, hereinafter described, by means of conductors 81 and 88.

'I'he condenser 16 (and associated condenser 8| or 82, if used) must be discharged automatically when the diierence of potential across the same reaches a predetermined value which pro duces the maximum desired horizontal deflection of the electron beam in the oscillograph tube. Such discharge is effected through a grid-controlled recter or triode 89, the plate of which is connected through the conductor 6| and the primary winding of the transformer 62 to the ground conductor 24. The grid of the triode 89 is at a fixed but adjustable potential which is negative with respect to ground, as determined by the setting of a potentiometer 90, the terminals of which are respectively connected through the conductors 24 and 85 to the same relatively high voltage direct current source which is connected to the pentode 11 and the condensers 16, 80, and 8|. The adjustable contact of the potentiometer 90 is connected through the secondary winding of a transformer 9| to the grid of the triode 89. The cathode and one side of the lament of this triode are connected to the ungrounded sides of the condensers 16, 80, and 8|, that is, to the conductor 19. The lament is connected by means of conductors 92 `and 99 to a suitable source of lament current hereinafter described.

At the instant when the condenser. l v(ref-- erence to which hereinafter will be understood to include also` the condensers 88 and 8| if one of the latter is being used) begins to charge, or immediatelyafter a discharge thereof, the cathode of triode 89 is substantially at ground potential. When de-ionization is complete the tube is non-conducting and the condenser 'i6 begins to charge. As the condenser 'l5 charges the potential of the cathode of tube 89 becomes increasingly negative with respect to ground, eventually reaching a value in the neighborhood of thevugrid potential. This tube, is of a type which ionizes when its grid is at a predetermined negative potential with respect to its cathode for some n'predetermined positive anode potential, and thereupon suddenly becomes conducting, and the condenser 1,6 is then rapidly discharged therethrough. This device, therefore, serves to reduce the difference of potentialbetween the X plates ||e of the oscillograph rapidly to zero by discharging the condenser 18 when such potential reaches its predetermined maximum value.

It is necessary that the sweep frequency be either the same as or a sub-multiple of the frequency of the waves to be observed; otherwise the electron beam in the oscillograph will not retrace the same path each time it crosses the screen. This condition may be approximately realized by manipulation of the potentiometer 83, but it is desirable to interlock the sweep circuit with the signal circuit to prevent the wave from Varying in position. `This is accomplished by means of a triode amplifier 9d, such as a type 56 triode, which is controlled from the signal circuit through the previously-mentioned conductor 54 and an insulating condenser 95, one

of the terminals of which is connected to said of the controlling signal.

conductor and the other terminal of which is connected to one end of a potentiometer 96. The other terminal of said potentiometer is connected to the conductor 85 and the adjustable contact of the potentiometer is connected to'the grid of the triode 94.

The cathode of the triode 94 is connected through a resistor 91 to the conductor 85. The plate of the triode 94 is connected through the primary winding of the transformer 9| and a resistor 98 in series therewith to the ground conductor 2li and a condenser 99 is connected between the junction point of said transformer winding and resistor and the cathode of the triode. The filament of the triode is connected through conductors |00 and |0| `to a suitable source of filament current described hereinafter.

By means of this arrangement, a portion of the current from one of the signal circuits is utilized to control the triode 94, the plate current of which is introduced through the transformer 9| into the grid circuit of the triode 89. The amount of current thus introduced into the grid circuit of the triode 89 is controllable by the poltentiometer 96 in the grid circuit of the triode 94. This introduction of current into the grid circuit of the tube 89 under the control of one of the signal circuits insures that said tube always breaks down at the same point on the cycle The other signal will be of the same frequency or a multiple or submultiple thereof and therefore the breakdown of the tube 89 will always occur at the same point on the cycle of this signal as weil as on the cycle of the first signal.

In addition to amplifying the signal current to the system, as hereinbefore referred to.

accesso 'ment such as a transformer were used to introduce the signal current .into the grid circuit of tube l89.V f. Y

` A power transformer .|02 is utilized to supply the filament currents and the high voltages required for the operation of the various devices of This transformer comprises a primary winding |02a, which is connectedthrough a main switch ,|03 and terminals |04 to any suitable alternating current source. The transformer |02 comprises a number of secondary windings |02b to |0211., inclusive, the connections of which will now be described.

The secondary winding |0217 is connected to conductors 48 and 09 to supply the filament current for the amplifiers 25, 26, 21, and 28. The secondary winding |020 is connected to conductors 1| and 12a, the latter being connected through a variable resistor |05 to the conductor 12 to furnish the filament current for the triodes 51 and 58. The secondary winding |02d is connected through the primary winding of a transformer |08 and thence through a variable resistor |07 to the filament ||b of the cathode ray oscillograph tube The variable resistor |01 is utilized to adjust the lament current of the cathode ray tube and the transformer |06 serves merely to insulate an ammeter |0601, which is connected in the secondary circuit of the transformer to indicate the filament current value, from the high voltage circuits.

The secondary winding |02e is connected to conductors 81 and 88 to supply the filament current for the pentode 11, and the winding I02f is connected to conductors 92 and 93 tosupply the filament current for the triode 89. The secondary winding |02g is connected to the filament of a triode |08 which is described hereinafter,

l and the winding |02h is connected to conductors vrectifier |09, which may suitably consist of a type 280 rectifier tube, and which derives its filament current from the transformer secondary winding |027. The direct-current leads of this rectifier comprise one branch of the conductor 24, which is the positive side of the direct current source, and a conductor ||0, which is the negative side. The conductor ||0 extends to a center tap on the transformer winding |021 and the positive side of the circuit is connected to the center tap of the usual lament bridging resistor associated with the rectifier |09. A lter system comprising inductances ||2 and I3, condensers H4, ||5, and IB, and a resistor is included in the direct-current circuit.

The'secondary windings |027c. and |021 of the transformer |02 are utilized in connection with a full-wave rectifier ||8 in the same manner described above with reference to the transformer windings |021i and |027', in connection with the rectifier |09. The rectifier I8 may likewise suitably consist of a type 280 rectifier tube and the rectifier and lter system similarly includes a center tap filament bridging resistor ||9, inductances |20 and 2|, condensers |22, |23, and |24, and a resistor |25. This arrangement impresses a direct current potential upon conductors 43a and 69, the former being the positive side of the circuit and being connectible to the conductor 43 through a switch which is described hereinafter.

The transformer secondary windings |02m and |0211. are utilized in conjunction with a rectifier |26 which may suitably consist of a type 866 half-Wave rectifier tube. This rectifier serves as a high-voltage, direct-current supply for the cathode ray tube and the requirements with respect to this source are such that no inductance is necessary in the filter, there beng'merely a condenser bank comprising condenser.: |21,

|28, and |29 and a voltage divider comprising resistors |30, |3|, |32, and |33, connected across the output terminals of the rectifier. The transformer winding |0211. constitutes the source of filament-current supply for the rectifier |26, and one side of the filament circuit is connected to a branch of the ground conductor 24 and constitutes the positive side of the high-voltage, directcurrent supply circuit. The negative side of said circuit is derived from one terminal of the highvoltage transformer winding |02m and is connected through a conductor |34 to one side of the filament IIb of the cathode ray tube The other terminal of the transfermer secondary .winding |02m is connected through a switch,

hereinafter described, and resistors |35, |36, |31, |38, |39, and |40 to the plate of the rectifier tube |26. 'I'he resistors |35 to |39, inclusive, constitute the steps of a variable resistor which controls the output voltage of the rectifier and also stabilizes the operation thereof. A rectifier of this character has a tendency to conduct only at intervals when very lightly loaded, when no series resistance is used.

The resistors |30, |3|, |32, and |33 insure an equally-distributed load on the condensers |21, |28, and |29. 'I'he resistor |32 is also utilized as a potentiometer for supplying a variable intermediate voltage for the rst anode ||d of the cathode ray tube said resistor |32 having a variable tap connected through a conductor |4| to said anode.

In addition to the elements described above, the system preferably comprises a time-delay circuit for delaying the application of the high voltages to the cathode ray tube and to the various heater type tubes of the system until the cathodes thereof are well heated. This portion of the system preferably comprises a switchoperating motor |42, the winding of which is indicated at |42a. One terminal of thisiwinding is directly connected through a conductor |43 to one of the alternating current supply terminals |04, and the other terminal of said winding is connected through contacts |440.' of a control relay |44 and a conductor |45 to the other side of the alternating current supply circuit, at a point inside the main switch |03, so that this circuit is deenergized when said main switch is opened.

The actuating coil of the control relay |44 has one of its terminals connected to the ground conductor 24 and its other terminal connected to the plate of the triode |08. This triode serves t furnish the desired time delay, because the plate current therein builds up very slowly due to the circuit arrangement utilized. When the main switch of the system is closed the direct-current voltages furnished by the rectii-lers are established substantially immediately and the output voltage of the rectifier |09 is applied to the plate of the triode |08, the positive side of this circuit extending through the ground conductor 24 and the winding of the control relay 44 to the plate of the triode |08, and the negative side of the circuit extending through the conductor ||0 and a resistor |46 to the lament of the triode. When the plate current starts to flow there is a voltage drop across the resistor |46, which causes a negative bias to be applied to the grid of the triode |08 through a condenser |41. If there were no way for the biasing voltage to leak off of the grid the plate current would reach a steady state immediately, at some low value determined by the total plate voltage and the bias, but with the connections shown the condenser |41 will gradually charge through a resistor |48 and as it does so the negative`bias decreases, allowing the plate current to increase. An increase in the plate current will cause an increase in the drop across the resistor |46 and the los's of bias will be partly counteracted thereby. Thus, the rise of plate current is 'very gradual. Eventually the grid will be at lament potential (zero bias) and the plate current will then be at its maximum value.

'Ihe control relay |44 will not operate to close its contacts |44a until the current flowing in its actuating winding |44, which is the plate current of the triode |08, reaches a predetermined value. The circuit is so designed that the plate current of the triode |08 will not reach this predetermined value until4 the desired time delay after the closing of the main switch |03 has elapsed and, therefore, the closing of the contacts |44a is delayed for said desired period.

Upon the closing of the contacts of the control relay |44 the winding of the switch-operating motor |42 is connected directly across the alternating current-supply circuit terminals |44 and said motor operates through suitable gearing indicated at |42b to close a plurality of pairs of contacts |42e, |42d, and |42e. The contacts |42e are connected in the direct-current output circuit of the rectifier |09, between the negative output conductor ||0 and the conductor 85, which extends to the various elements of the system to be connected to this direct-current source. The contacts |42d are connected in the positive side of the direct-current output circuit of the rectifier ||8 between the conductors 43 and 43a, and the contacts 42e constitute the previously-mentioned switch in the plate circuit of the halfwave rectifier |26.

When the switch contacts |42e, |42d, and 42e are closed, all of the direct-current supply circuits are completed and the system is ready for operation Under this condition the switch-operating motor |42 is blocked from further operation but this motor is of such a design that it can remain in this condition indenitely. The switch contacts, therefore, remain closed as long as the main switch |03 is closed. Upon opening of the switch |03 the motor winding |42e is deenergzed and the switch contacts are opened through the action of gravity and the elasticity of the contacts.

The conductor |4| hereinbefore referred to as supplying a variable intermediate voltage for the first anode Ild of the cathode ray tube II, in

aiddition to being connected directly to said anode Ild, is connected through voltage dividing resistors |49 and |50 to one side of the lament or cathode IIb of the tube The junction point of the resistors |49 and |50 is connected to the auxiliary electrode llc, so that the desired intermediate voltage is applied thereto.

One of the plates of each pair of defiecting plates IIe and IIf of the cathode ray tube is connected directly to the ground conductor 24. The other plate of the pair IIe is connected through a pair of normally closed jack contacts to the output conductor 'I9 of the sweep circuit, as hereinbefore indicated. The second or ungrounded plate of the pair of deilecting plates IIf Ais connected through normally closed jack contacts |52 to the output conductor 53 of the signal amplifying and commutating circuitsystem. A bridging resistor |53 is connected between the conductor 53 and the ground conductor 24 and therefore is connected directly across the deilecting plates IIf when the4 jack contacts I 52 are closed forthe normal operation of the system.

The jack contacts |5| and |52 are provided in order to accommodate the use of the cathode ray tube II in connection with external circuits, if desired. In that event the detlecting plates IIe and II f ofthe cathode ray tube are disconnected from the system herein illustrated, by reason of the opening of thev jack contacts I 5I and |52 incident to the insertion of plugs in the respective jacks. A suitable double contact plug is utilized in each case, one of the terminals of one plug making contact with a contact memberl |54 and the other contact of the same plug making contact with an associated contact member |55, whereby the leads of said plug are connected directly to the respective deilecting plates of the pair IIe. A similar plug may be utilized to make external connections in a similar manner through jack contacts |56 and |51 to the respective plates of the pair IIf.

The metallic oating IIg on the inside of the iiaring portion of the tube I is connected through a resistor |58 to the ground conductor 24 and a return path for the electrons is thereby provided. This provision eliminates instability of operation of the tube and improves the sharpness of the beam by reason of the negative potential which. is impressed upon the conducting coating IIg.

In the operation of the above-described system for the. observation of two waves, the' signal voltages are respectively applied to the two sets of terminals I2, I3 and' I4, I5 and the variable resistors I8 and 22 and potentiometers I9 and 23 should be initially adjusted so thatthe signal input to the system is reduced to as low a. value as possible. In other words, the variable resistors |8 and 22 will be adjusted to interpose the maximum series resistance in the corresponding signal circuits and the potentiometers I9 and 23 will be adjusted so that the minimum resistance is connected between the movable contacts thereof and the common connection therebetween,

'which constitutes a branch of the ground conductor 24.

The main power switch 983 of the system is then closed, and after a predetermined time delay has 'elapsed the motor-operated switch contacts |42c, |42d, and |42e will be automatically closed in the manner hereinbefore described. Ordinarily at this point a broad stripe of light will appear across the screen of the oscillograph tube II. This indicates that the commutator circuit has not begun tooperate and the operation of this portion of the system is started by opening one of the switches 59 and 60 momentarily. These switches may be conveniently associated with a single dialA which m'ay be turned in either direction to open either one of the two switches.

Upon reclosing of the switch which has been opened, the commutator circuit will begin to operate normally, and ordinarily two axes will appear on the oscillograph screen. 'I'hese two axes are brought together by adjustment of the potentiometer 4l. Thereupon the potentiometer 23 may be turned slowly away from its minimum position until a signal of desirable amplitude appears. If the signal is so weak that it does not give sumcient amplitude, the variable resistor 22 maybe adjusted to obtain a further increase. The potentiometer 83 is then to be adjusted until the desired number of cycles appears on the screen, and at the same time the travel of the Wave is reduced to a minimum. 'I'he last trace of travel should then be eliminated by adjusting the potentiometer 95 to increase the amount of signal current introduced into the sweep circuit, but only to the extent necessary to make the wave stationary on the screen. The introduction of an eX- cessive amount of signal current into the sweep circuit will shorten the sweep. The potentiometer I9, and also the variable resistor I8 if necessary, may now be adjusted to bring the other signal up to any desired amplitude.

In order to make certain that the two signals appear in their true phase relation (avoidingany possible stabilization of the waves in false relative positions) it is advisable to vary the potentiometer 83 and to note the phase relationship for various speeds of sweep with the commutating circuit'not operating, and when the potentiometer 83 is nally set as desired, to select a setting which gives what appears to be the true phase relationship, under most desirable conditions of speed of sweep and stabilization. This should be done carefully, bringing the sweep frequency as near as possible to the exact desired value before locking in with the synchronizing signal control. Starting the commutating circuit in operation should then have no eiect upon the signal already being shown. The phase of one signal may be reversed by means of the reversing switch 39.

The controls 1|), 82, 86, 90, |05, |01, |32, and I 35-I39 ordinarily require no operating adjustments. The variable resistor 'I0 controls the bias on the grid-controlled rectiers 51 and 58. The tap switch 82, which may be used to vary the capacity of the condenser bank in the sweep circuit,'is preferably adjusted to give the maximum capacity at which the slowest sweep is obtained with a given setting of the potentiometer 83, and thereafter seldom requires any further adjustment. The potentiometer 86 controls the screen voltage of the pentode ,'I'I, which seldom requires adjustment. The potentiometer 90 varies the length of the sweep and does not require adjustment during ordinary operations. The variable resistor |05 may be utilized to vary the filament current of the grid-controlled rectiers 51 and 58, but usually such adjustment is not necessary. 'Ihe Variable resistor |01 serves to control the amount of current supplied to the lament IIb of the cathode ray tube |I, which likewise generally requires no adjustment. The filament current should be adjusted to a value between 2.5 and 3 amperes and may be read by means of the ammeter |0611.. The potentiometer I 32 and the variable resistance I35|39 respectively control the voltage applied to the lrst anode IId and to the cathode IIb of the cathode ray tube and these values likewise seldom require change after a satisfactory operating condition has been obtained.

With the system described above, signals of different frequencies may be observed if one is a harmonic of the other. In that event the circuit carrying the signal of the lower frequency should be connected to the terminals I4 and I5, since the synchronizing signal is supplied to the 5 sweep circuit from the amplifier connected to said terminals.

From the foregoing physical description of the system it will be seen that' each of the signals to be observed passes through two amplifier stages before reaching the deflecting plates of the cathode ray tube. These amplifiers, 25, 26, 21, and 28, alternately block and operate normally so that first one signal is transmitted and then the other. 'I'he commutating circuit, comprising the gridcontrolled rectifiers 51 and 58, controls the bias on the said amplifiers, thus effecting the desired commutation.

This operation is accomplished by the design and adjustment of the sweep circuit, which causes a voltage wave of saw tooth form to be impressed upon the X plates I Ie of the cathode ray tube, in the manner hereinbefore described.

The operation of the commutating and amplifying circuits under `the control of the sweep circuit may be described by assuming that at the start the rectifier 58 is conducting and that the rectifier 51 is not conducting. When the condenser 16 in the sweep circuit discharges, the surge is transmitted through the air-core transformer 62, 64 and impressed upon the grids of the rectifiers 51 and 58 through the condensers E5 and 66. The polarity of the air-core transformer is such that the surge sent to the grids is positive, and if the biasing resistor 10 is adjusted correctly, the rectifier 51 will become conducting.

The total voltage across the commutating circuit may suitably be about '15 volts, and the voltage across a conducting grid-controlled rectifier of the type herein referred to is about l5 volts. Therefore, the plate of the rectifier 51, which was at ground potential when the tube was not conducting, must fall to approximately 60 Volts below ground potential when the tube breaks down.

The plate of the rectifier 58 was already 60 volts below ground, so that at the instant after the' 55 rectifier 51 has started, the plate of the rectifier 58 must be approximately 120 volts below ground, since condensers act as short circuits for an infinitesimal amount of time after a voltage is applied thereto. The condenser 15 immediately 60 starts charging to its new state of equilibrium through the resistors 13 and 14, and the charging time, although small, is appreciable, so that before the plate of the rectifier 58 has come up to a positive potential with respect to the cathode thereof, the gas in the tube has de-ionized, rendering the tube non-conducting.

Now the circuit is in a steady state, and the next surge from the sweep circuit will cause the current to shift back to the rectifier 58 in the same manner. It is evident, therefore, that the points 55 and 56, to which the grids of' the second-stage amplifiers 21 and 28 are respectively connected, are alternately at ground potential and at a potential approximately 60 volts below ground.

Therectiiiers 51 and 58 are, inn turn, controlled by the sweep circuit, the ar- When the point 55 is at ground potential the amplifier 21 will have the normal bias provided by the resistor 45 and will amplify its signal and communicate the same to the Y plates Ilf of the cathode ray tube II. At the same time the amplifier 28 will have an extra negative bias of approximately 60 volts by reason of the connection of the grid of said amplifier to the point 55 in the commutating circuit, which at that time is at a. potential of approximately 60 volts below ground potential. This extra negative bias on the grid of the amplifier 28 is sufficient to cut off the plate current in said amplifier, so that no signal current can get through the same. When the commutating circuit operates, the situation is reversed and the first signal is blocked and the second one passed. i' i' It will be seen, therefore, that the signals which are respectively impressed upon the terminals I2, I3 and I4, I5 are alternately impressed, after being suitably amplified, upon the Y plates of the cathode ray tube, and that the commutation between the two signal circuits takes place at the end of each sweep of the electron beam across the viewing screen, the horizontal sweep of the beam across the screen being effected at constant speed and at regular intervals synchronized with the frequency of the signals, by reason of the operation of the sweep circuit.

The operation of the cathode ray tube, therefore, is so controlled by the system disclosed that the electron beam traces the wave form of one of the two signals on each alternate sweep across the viewing screen, and traces the wave form of the second signal on each other alternate sweep. These sweeps are made so rapidly that the persistence of vision makes it appear that the two waves are' being traced simultaneously and continuously upon the viewing screen, and this effect may be enhanced by the use of screen materials which, in themselves, possess some degree of persistence of fluorescence. In any event, the visual effect of the operation of the system is that of absolutely simultaneous and continuous observation of two waves in their true phase relationship. This eect will be recognized as a highly novel and extremely desirable accomplishment in the utilization of cathode ray oscillographs controlled by purely electrical systems.

The system shown in Fig. 1 is adapted for the observation of alternating current waves and a1- ternating components of signals of various kinds. Said system may be readily modified, however, to accommodate the observation of direct current signals or composite signals of any kind. In order to accomplish this result, it is merely necessary to modify the amplifying and commutating circuits of the system, and Figs. 2, 3 and 4 of the drawings illustrate suitable modifications of said circuits.

Each of these figures shows a modified arrangement of the amplifying and commutating circuits, which may be bodily substituted for the portion of the previously-described system enclosed by the dot-and-dash lines in the upper lefthand corner of Fig. l. In considering these modifications, therefore, it will be understood that the complete system in each case will be the same as that shown in Fig. 1, with the exception of the said upper lefthand portion thereof and with the slight further exception that in utilizing these modications a minor change is made in the connections of one of the deflecting plates IIf of the cathode ray tube II, all as fully described hereinafter. The modifications shown in Figs. 2, 3 and 4, in addition to providing for the observation of alternating and composite signals, include various other features of advantage, as will presently appear.

In describing Figs. 2, 3 and 4 of the drawings, the same reference characters used in connection with Fig. 1 will be applied to the various parts ofthe systemin so far as the same are identical With the corresponding parts of Fig. 1.

Referring to Fig. 2, the signal circuit connections ,are provided through terminals I2, I3, I6, and I5, and potentiometers |59 and |69 are connected across the terminals I2, I3 and I4, I5, respectively. In this system single-stage ampliers are used in place of the two-stage ampliers of Fig. 1. These single-stage ampliers are constituted by pentodes I 6| and |62, the control grids of which are connected to the movable contacts of the potentiometers |59 and |60, respectively.

A small battery |63, such, for example, as a 3-volt battery, may be utilized to supply the bias voltage for the pentodes |6| and |62, said battery having its negative terminal connected to the ground conductor 24 and its positive ter-v minal connected to the cathodes of both of the n tubes |6| and |62, the same point being also connected in the conventional manner to a midpoint tap on a resistor |64 which is connected across the lament-supply circuit of the tubes.

This filament-supply circuit is constituted by' the conductors 48'and` 49, as in Fig. 1.

A connection extends from the grid of the pentode |62 to the conductor 54 and serves the purpose of synchronizing the sweep circuit with the signals being observed, as previously de scribed in connection with Fig. 1.

The plates of thepentodes |6| and |62 are connected directly to the conductor 53, which extends to one of the Y plates IIf of the cathode ray tube as before. The plate voltage for the pentodes |6| and |62 is supplied from the highvoltage, direct-current supply conductor 63 through a load resistor |65. I

The screen of the pentode |6| is connected through a resistor |66 to the point 55, which is the same point in the circuit as that designated by the Asame reference character in Fig. 1, and the screen of pentode |62 is connected through a variable resistor |61 to the point 56 of thel system. These points 55 and 56 are connected to the plates of triodes 51 and 56 in the same manner as in Fig. l, except that here only one of these connections is provided with a control switch, namely, the switch 59 in the connection from the point 55 to the plate of the triode 51. This switch may be located in either of the two connections referred to, and will serve'the same purpose as the two switches 59 and 60 in Fig. 1.

Between thel points 55 and 56, two resistors |68 and |69 are connected in series, and the junction point therebetween is connected to a tap on a voltage-divider |10, the terminals of which are connected to the high-voltage, directcurrent supply terminals 43 and 69, respectively. The conductor 69 constitutes the negative side of -this supply circuit, and the point to which the junction point of resistors |68 and |69 is connected may suitably be at a potential of about 75 volts positive with respect to said conductor 69. A condenser |1| is also connected between the points 55 and 56. 'I'his condenser corresponds to the condenser 15 of Fig. 1, and the resistors |68 and` |69 correspond to the resistors 13 and 14 of Fig. 1.

'Ihe filaments of the triodes 51 and 58 are connected in parallel across the filament-supply circuit constituted by the conductors 1| and 12, and a lament-brldging resistor |12 is connected across this circuit with a mid-point tap connected to the cathodes of the tubes 51 and 58 in the usual manner. 'Ihese cathodes are connected to the negative direct-current supply conductor 69 through a variable resistor |13, similar to the variable resistor 16 of Fig. 1..

The air-core transformer 62, 64 is utilized as in Fig. 1, but the secondary connections thereof are somewhat different. One side of the secondary winding is connected directly to the grids of both of the triodes 51 and 58 and the other terminal of said secondary Winding is connected to the negative direct-current supply conductor 69.

The only other difference between the circuits of Fig. 2 and the corresponding portion of Fig. 1 is in the connection of the upper one of the deflecting plates IIf of the cathode ray tube II. This upper deflecting plate, instead of being connected to the ground conductor 24, as shown in Fig. 1, is connected to a variable tap on a potentiometer |14, the terminals of which are respectively connected to the high-voltage, direct-current supply conductors 43 and 69.

The operation of the circuits of Fig. 2 is similar to that of the corresponding portion of Fig. 1, but it will be seen that the connections are such that direct-current signals and components of signals may be observed as well as alternatingcurrent signals. 'I'he number of electron tubes utilized in the system has been reduced by the substitution of the single-stage amplifiers constituted by the pentodes |6| and |62, for the double-stage amplifiers constituted by the triodes 25, 26, 21, and 28 of Fig. 1. In connection with the pentodes |6| and |62, the resistor |66 serves to reduce the screen voltage applied to the pentode |6| and the variable resistor |61 performs the same functionfwith respect to the pentode |62. In this way, the variable resistor |61 provides a means of balancing the plate currents of the two pentodes, whereby the axes of the two signals to be observed are made to coincide on the viewing screen of the oscillograph tube The connection of the upper one of the deiiecting plates ||f to the movable contact on the potentiometer |14 permits the axis of the wave under observation to be shifted vertically on the screen.

The operation of the commutating circuit, comprising the triodes 51 and 58, is the same in l Fig. 2 as in Fig. 1, and these commutators serve alternately to reduce and restore the screen voltage on the pentodes |6| and |62, whereby said pentodes are caused alternately to pass and block the signals of the respective signal circuits to which they are connected, thus causing the oscillograph to give alternate traces of the two signals under observation, just as in the system shown in Fig. 1.

The modicatlonof the amplifying and commutating circuits shown in Fig. 3 is similar in most respects to that shown in Fig. 2, as indicated by the extent to which similar reference characters are used. The diierences reside in the manner of supplying direct-current potentials toV various parts of the system. A voltage divider |15, as illustrated in Fig. 3, is connected between the high-voltage, direct-current supply conductors 43 and 69, and various intermediate connections are made to the same at points |15a, |15b, I15c, and |15d.

A potentiometer |16 is connected between the negative end ofthe voltage divider |15 (conductor 69) and the point |15a, and a potentiometer |11 is connected between the points I15a and I15b. A conductor |18 extends from the movable contact of the potentiometer |16 to one terminal 'of the secondary winding 64 of the aircorc transformer 62, 84, and replaces the conncction `of said terminal, shown in Fig. 2, directly to the negative direct-current supply conductor l 69. The movable contact of the potentiometer |11 is connected through a conductor |19 to the ground conductor 24.

The point |a on the voltage divider |15 is connected directly to the cathodes of the com- 15 mutating triodes 51 and 58, instead of connecting said cathodes to the negative direct-current supply conductor 69 through the variable resistor |13 of Fig. 2. A conductor |80 extends from the point |1513 on the voltage divider |15 to the cathodes of the pentodes |6| and |62 and supplies a suitable biasing voltage for said pentodes, thus eliminating the battery |63 of Fig. 2.

The point |15c on the voltage divider |15 is selected to give a suitable potential, such, for example, as about 15 volts positive with respect to the negative supply conductor 69, and this point is connected to the junction point between the resistors |68 and |69, the same as in Fig. 2. The point |15d of the voltage divider is connected to the upper one of the deecting plates ||f of the cathode ray tube Il, thus replacing the potentiometer |14 of the modification shown in Fig. 2. This point |15d is selected to give the desired negative potential with respect to the positive supply conductor 43, such, for example,

as approximately 200 volts.

With the above-noted exceptions, the apparatus and circuit connections shown in Fig. 3 are the same as those shown in Fig. 2, and the operation of the system as thus modified is likewise essentially the same. The potentiometer |16 serves to regulate the grid bias of the triodes 51 and 58, and the potentiometer |11 provides a,

means of adjusting the grid bias on the pentodes IBI and |62. The connection of the deflecting plates ||f of the cathode ray tube in the manner described, renders the same responsive to changes in the difference of potential across the load resistor |65 in the plate circuit of the pentode amplifiers |6| and |62,the connection of the upper one of the plates ||f to the point |15d on the voltage divider being such as to give a suitable neutral position of the cathode ray beam in the oscillograph tube. The voltage drop across the resistor |65, plus the voltage drop across the portion of the voltage divider between the point |15d and the positive terminal, connected to the positive supply conductor 43, gives4 the total voltage applied to the plates Hf, which varies according to the amplitude of the signal under observation. The horizontal deflection of the cathode ray beam, therefore, is always governed by the amplitude of the signal which is being passed by one or the other of the amplifiers |6| and |62.

Fig. 4 shows a further modification of the amplifying and commutating circuits whereby three waves or signals may be observed simultaneously, instead of two, as in Figs. 1, 2, and 3.

The modifications required to render the system suitable for the observation of three waves are slight and may be made without difl'iculty. The arrangement and operation are fundamentally the same, being merely extended to provide connections to three signal circuits and to provide means for subjecting the deflecting plates ||f of the oscillograph to the effects of the three signals in predetermined sequence and in rapid succession, as is done with two signal circuits in the systems previously disclosed herein.

In the system of Fig. 4 three amplifiers and three commutating tubes are provided and are respectively associated with the three signal circuits. At the end of each sweep of the cathode ray beam across the viewing screen a surge or impulse is transmitted by the sweep circuit to the commutating circuit, just as in the previously-described systems, and the commutating circuit then functions to switch the next signal circuit into operative connection with the oscillograph. This operation is repeated continuously in a predetermined cycle, so that the cathode ray beam of the oscillograph makes one trace across the viewing screen under the inuence of the first signal, makes its next trace under the influence of the second signal, and makes its third trace under the influence of the third signal, whereupon the operation is repeated in continuous cycles, so that any given signal is traced on the screen on every third sweep of the beam.

The system of Fig. 4 comprises three pairs of -signal circuit terminals, comprising a first pair |8| and |82, a second pair |83 and |84, and a third pair and |86. Potentiometers |81, |88,

and |89 are connected across the respective pairs of signal circuit terminals and the movable contacts of these potentiometers are respectively connected to the grids of three pentode amplifiers |90, |9|, and |92. The signal for synchronizing the sweep circuit with the signal circuits is taken from the grid connection of the amplifier |92, through the conductor 54, in the same manner as in the systems hereinbefore described.

The filaments or heaters of the pentodes |90, I9|, and |92 are connected in parallel across the filament-supply conductors 48 and 49, having the usual lament-bridging resistor |64 connected thereacross, with the mid-point tap of the latter-connected to the cathodes of all of these amplifier tubes. The bias of these tubes is provided by a connection extending from said cathodes to a point |93a on a voltage divider |93, the terminals of which are respectively connected to the conductors 43 and 69 of the high-voltage, direct-current supply circuit.

The plates of the amplifiers |90, |9I, and |92 are all connected together and through the conductor 53 to the lower one of the Y plates I lf of the cathode ray tube, as in Figs. 2 and 3. The plate voltage for the amplifiers is supplied by the supply conductor 43 through the load resistor |65, also as in Figs. 2 and 3.

The screen of the amplifier tube is connected through a resistor |94 to the plate of a triode |95 and the screen of the amplifier |9| is connected through a variable resistor |96 to the plate of a triode |91. The screen of the amplier |92 is connected through a variable resistor |98 and a normally-closed switch |99 to the plate of a triode 200. l

'I'he pentodes |90, |9|, and |92 are similar to the pentodes |6| and |62 of Figs. 2 and 3, and the triodes |95, |91, and 200 of Fig. 4 are similar to the triodes 51 and 58 of Figs. l, 2, and 3. The switch |99 in Fig. 4 is provided for the same purpose as the switches 59 and/or 60 in the previous figures.

The plate leads of the triodes |95, |91, and 20D, which also constitute the screen supply leads for the amplifiers |90, |9|, and |92, are designated by the reference characters 20|, 202, and 203, respectively, and are respectively connected through resistors 204, 205, and 206 to a tap |9317 on the voltage divider |93, whereby the screen Y voltages for the amplifiers |90, |9I and I 92 are supplied. The conductors 20|, 202, and 203 are also interconnected by circuits providing the deysired cyclical operation of the commutating system. l These interconnecting circuits comprise a connection between each pair of the three conductors 20|, 202, and 203, and each of these connections includes a rectifier, a condenser and a resistor, all in series, and another resistor connected in parallel relation to the rectifier.

These elements comprise a rectier 201, a reconsist of copper oxide rectiers which constitute one means of transferring the impulses from the plate circuit of one of the commutating triodes to the next one in the predetermined sequence of operation, without aiecting the triode preceding it in said sequence. The resistors 208, 2 I2, and 2I6 shunting the rectiers 201, 2| I, and 2|5, respectively, are provided to eiiect charging of the condensers 209, 2I3, and 2I1 between the impulses, and the series resistors 2 I0, 2 I4, and 2 I8 reduce the amplitude of the impulses from the plates vof the respective triodes in order to prevent ,the extinguishing of both of the other triodes thereby. The laments or heaters of the triodes |95, |91, and 200 are all connected in parallel across the lament-supply circuit constituted by the conductors 1| and 12, the usual filament-bridging resistor |12 being also connected across said circuit, with a mid-point tap connected to the cathodes of the tubes |95, |91, and 200. 'Ihese cathodes are connected through a common variable resistor 2 I9, corresponding to the similarly connected Variable resistors 10 of Fig. 1 and |13 of Fig. 2, to the negative supply conductor 69.

The air-core transformer 62, 64 is utilized in this system as in the other circuit arrangements hereinbefore disclosed, and one terminal of the secondary winding 64 of said transformer is connected to the grids of all of the triodes |95, |91, and 200. The other terminal of said secondary winding is connected to the negative conductor 69 of the high-voltage, direct-current supply circuit, as in Fig. 2. l

A potentiometer 220 is connected in parallel relation to the portion of the voltage divider |93 -between the point |9311. and the negative supply conductor 69, and the movable contact of saidv potentiometer is connected to the ground conductor 24 in the same manner and for the same purpose as in the case of the potentiometer |11 in Fig. 3.

Ihe upper one of the deiiecting plates IIf in the system shown in Fig. 4 is connected to a movable potentiometer contact |93c on the voltage divider |93, which in this connection, therefore,

constitutes a potentiometer also. This deiecting plate connection is similar to that illustrated in Fig. 3, except that it provides for adjustment of the total potential difference applied to the de- 203. The rectiiiers 201, 2| I, and 2|5 may suitably4 fleeting plates, in somewhat the same fashion as is provided by the use oi.' the separate potentiometer |14 in Fig. 2.

The amplifying and commutating system shown in Fig. 4 is very similar in operation to that of Fig. 3. 'I'he only point which is believed to require explanation is that having to do with the manner in which the triodes |95, |91, and 200 are red in predetermined sequence, as desired. To obtain a clear understanding of this point it may be assumed that at a given moment the triode |96 is non-conducting and that the triodes |91 and 200 are conducting. Under these conditions the amplifier will be passing the signal of the associated signal circuit, connected to the terminals 0| and |92, to the oscillograph observation circuit, while the amplifiers |9I and |92 will be blocking the signals of the signal circuits respectively associated therewith..v

Now, at the end of the sweep of the electron beam in the cathode ray tube, as determined by the operation` of the sw'eep circuit, a surge is transmitted from the sweep circuit through the air-core transformer 62, 64 to the gridsv of the triodes |95, |91, and 200, and this surge ailects the triode to render the 'same conducting. The resulting sudden fall of potential of the plate of the triode |95 lowers the potential of the plate of triode |91 momentarily below-the discharge sustaining voltage, rendering ,said triode |91 nonconducting. However, 'the triode 200 is not ai'- iected at this time because the rectifier 2|5 prevents its plate voltage from being lowered'as a result of the above-mentioned sudden drop of the plate voltage-of the triode |95.

Therefore, during the next cycle of the sweep circuit the triode |91 will be non-conducting and the amplier'ISI will accordingly be conditioned to pass the signal of the signal circuit connected to the terminals |83 and |84 to the observation circuit, whereas the signals o'i.' the circuits connected to the terminals |8I, |02, and |05, |86 will be blocked by the ampliers |90 and |92, respectively. At the .end of. that cycle the surge from the sweep circuit to the commutating circuit willl restore the triode I 91 to conducting condition and render the triode 200 non-conducting, so that on the next ensuing cycle of the sweep circuit the third signal will be passed by the amplifier |92, while the rst and second signals will be blocked by the amplifiers |90 and |9I, respectively.

It will be apparent that this operation will go on in a. continuous cycle as long as the system is energized, so that the signals of the three signal circuits will be observed in the oscillograph in predetermined sequence during each complete cycle, consisting of three cycles of the sweep circuit. The oscillograph observation circuit, therefore, is subjected to the eiects of the three signal circuits inv rapid succession and predetermined sequence, so that the three signals will be observed simultaneously on the viewing screen of the osclllograph.

It is immaterial, of course, whether the se; quence proceeds in one direction, or the other,

-and it will be understood that the rectiflers 201 2II and 2|5 or other suitable means f or establishing the sequence may be arranged to provide either direction of progression, or random selection between the two possible directions, so long as the sequence remains constant throughout each continuous period of operation, after once being established for that operation. In any event, the sequence is predetermined as soon as the rst signal which happens to be observed is followed by the second, and that is the only limitation contemplated herein with reference to the sequential operation.

5 From all of the foregoing description it will be seen that the present invention provides means for controlling the operation of a cathode ray oscillograph of any ordinary type having a single electron beam established therein, in such manl ner that the beam is caused to trace the signals of two or more signal circuits in rapid succession to permit simultaneous observation of all of said signals on the viewing screen of the oscillograph, It is obvious, of course, that the system may be 15 extended to accommodate the observation of any number of signals. 'I'he objectionable effect of icker, which may become noticeable when the number of signals to be observed is considerably increased, may be retarded by utilizing, for the 20 fluorescent coating on the oscillograph viewing screen, a highly retentive material, whereby the traces produced thereon by the electron beam remain visible for longer periods of time. It will alsol be understood that the systems herein dis- 25 closed are not limited to the operation of oscillographs of the type in which only visual observation is provided, but that they are equally adaptable to oscillographs having provision for photographic recording of the signals traced by the 30 electron beam.

It should be clearly understood that the invention is not limited to the details of design or arrangement of parts herein disclosed, such disclosure being merely for the purpose of conveying 35 a clearer understanding of suitable embodiments of the invention. It will be apparent to those skilled in the art that various changes and moditlcations other than those herein disclosed may be made without departing from the spirit and 40 scope of the invention, and, in particular, that wherever numerical values of voltages and other quantities have been given herein, the same are merely given by way of example and not as limitations in any sense.

45 What is claimed as new and is`desired to secure by Letters Patent, therefore, is:

1. A cathode ray oscillograph system comprising connections to a plurality of signal circuits, an oscillograph observation circuit, and electronic 50 means operative automatically to subject said observation circuit to the effects of the signals of the diierent signal circuits ln rapid succession, whereby a simultaneous observation of said signals is aiorded 2. A cathode ray oscillograph system comprising connections to a plurality of signal circuits, an oscillograph observation circuit, and electronic means operative automatically to subject said observation circuit to the effects oi the signals 60 of the diierent signal circuits in rapid succession and in predetermined sequence, whereby a simultaneous observation of said signals is aiorded.

3. A cathode ray oscillograph system comprising connections to a plurality of signal circuits,

65 an oscillograph observation circuit, and electronic means operative automatically to subject said observation circuit 'to the effects of the signals of the diierent signal circuits in rapid succession, whereby a simultaneous observation of said sig- 70 nals is afforded, the switching from any one signal circuit to the next taking place at the end of a predetermined period of observation of the signal of said one circuit.

4. A cathode rayoscillograph system comprisu ing connectiomfk to a plurality of signal circuits.

an oscillograph observation circuit, and electronic means operative automatically to subject said observation circuit to the eiects of the signals of the different signal circuits in rapid succession. whereby a simultaneous observation of said signals is afforded, the switching between different signal circuits taking place at the end of each complete trace of any one signal.

5. A cathode ray oscillograph system comprising connections to a plurality of signal circuits, an electronic amplifier associated with each of said signal circuit connections, an oscillograph observation circuit connected with said amplifiers, and means for controlling said ampliiiers in predetermined sequence to cause the same to subject said observation circuit to the effects of said signal circuits. individually in corresponding sequence.

6. A cathode ray oscillograph system comprising connections to a plurality of signal circuits, an electronic ampliiler associated with each of said signal circuit connections, an oscillograph observation circuit connected with said amplifiers, and means for controlling the grid bias voltages of said ampliflers in predetermined sequence to cause the latter to subject said observation circuit to the effects of said signal circuits individually in corresponding sequence.

'7. A cathode ray oscillograph system comprising connections to a plurality of signal circuits, a two-stage triode amplifier associated with each of said signal circuit connections, an oscillograph observation circuit connected with said amplifiers, and means for controlling said ampliers in predetermined sequence to cause the same to subject said observation circuit to the effects of said signal circuits individually in corresponding sequence.

8. A cathode ray oscillograph system comprising connections to a plurality of signal circuits, a two-stage triode amplier associated with each of said signal circuit connections, an oscillograph observation circuit connected with said amplifiers, and means for controlling the grid bias voltages of the second stages of said amplifiers in predetermined sequence to cause the latter to subject said observation circuit to the eiects of said signal circuits individually in corresponding sequence.

9. A cathode ray oscillograph system compris- 5o ing connections to a plurality of signal circuits,

a multi-grid electronic amplifier associated with each of said signal circuit connections, an oscillograph observation circuit connected with said ampliers, and means for controlling said ampliers in predetermined sequence to cause the same to subject said observation circuit to the effects of said signal circuits individually in corresponding sequence.

10. A cathode ray oscillograph system comprising connections to a plurality of signal circuits, a single-stage pentode ampller associated with each of said signal circuit connections, an oscillograph observation circuit connected with said amplifiers, and means for controlling said amplifiers in predetermined sequence to cause the same to subject said observation circuit to the eiects of said signal circuits individually in corresponding sequence.

1l. A cathode ray oscillograph system com- 70 prising connections to a plurality of signal circuits. a pentode-ampliier associated with each of said signal circuit connections. an oscillogr-aph observation circuit connected with said amplifiers, and means for controlling certain of the auxiliary grid voltages of said amplifiers in predetermined sequence to cause the latter to subject said observation circuit to the effects of said signal circuits individually in corresponding sequence.

12. A cathode ray oscillograph system comprising connections to a plurality of signal circuits, an electronic amplifier associated -with each of said signal circuit connections, an oscillograph observation circuit connected with said amplifiers, and an electronic commutating circuit for controlling said ampliers in predetermined sequence to cause the same to subject said observation circuit to the effects of said signal circuits individually in corresponding sequence.

13. A cathode ray oscillograph system comprising connections to a plurality of signal circuits, an electronic amplifier associated with each of said signal circuit connections, an oscillograph observation circuit connected with said amplifiers, and an electronic commutating circuit for controlling said amplifiers in predetermined sequence to cause the same to subject said observation circuit to the effects of said signal circuits individually in corresponding sequence, said electronic commutating circuit comprising a gridcontrolled rectifier associated with each of said amplifiers and an inverter circuit control associated therewith.

14. A cathode ray oscillograph system comprising connections to a plurality of signal circuits, an electronic amplifier associated with each of said signal circuit connections, an Voscillograph observation circuit connected with said amplifiers, and an electronic commutating circuit for cc-ntrolling said amplifiers in predetermined sequence to cause the same to subject said observation circuit to the effects of said signal circuits individually in corresponding sequence, said electronic commutating circuit comprising a gridcontrolled rectier associated with each of said amplifiers and an inverter circuit control' associated therewith, and said inverter circuit control including unidirectional circuit-controlling devices insuring the predetermined sequential operation of the commutating circuit.

15. A cathode ray oscillograph system comprising connections to a plurality of signal circuits, an electronic amplifier associated with each of said signal circuit connections, an oscillograph observation circuit connected with said amplifiers, an electronic commutating circuit for controlling said amplifiers in predetermined sequence to cause the same to subject said observation circuit to the effects cf said signal circuits individually in corresponding sequence, an oscillograph timeaxis circuit, and an electronic sweep circuit for controlling said time-axis circuit.

16. A cathode ray-oscillograph system comprising connections to a plurality of signal circuits, an electronic amplifier associated with each of said signal circuit connections, an oscillograph observation circuit connected with said ampliiiers, an electronic commutating circuit for controllingsaid amplifiers in predetermined sequence to cause the same to subject said observation circuit to the effects of said signal circuits individually in corresponding sequence, an oscillograph time-axis circuit, an electronic sweep circuit for controlling said time-axis circuit, and a connection fromsaid sweep circuit to said commutating circuit to effect timing of the operation of the latter.

17. A cathode ray oscillograph system comprising connections to a plurality of signal circuits, an electronic amplifier associated with each of said signal circuit connections, an oscillograph observation circuit connected with said ampliiiers, an electronic commutating circuit for controlling said amplifiers in predetermined sequence to cause the same to subject said observation circuit to the effects of said signal circuits individually in corresponding sequence, an oscillograph timeaxis circuit, and an electronic sweep circuit for controlling said time-axis circuit, said sweep circuit comprising a condenser and charging means therefor to give the desired timing action.

18. A cathode ray oscillograph system comprising connections to a plurality of signal circuits, an electronic amplifier associated with each of lsaid signal circuit connections, an oscillograph observ-ation circuit connected with said ampliiiers, an electronic commutating circuit for controlling said amplifiers in predetermined sequence to cause the same to subject said observation circuit to the effects of said signal circuits individually in corresponding sequence, anY oscillograph time-axis circuit, and an electronic sweep circuit for controlling said time-axis circuit, said sweep circuit comprising a condenser, charging means therefor to give the desired timing action, and means operating suddenly to discharge said condenser when the voltage of the charge thereof reaches a predetermined value.

19. A cathode ray oscillograph system comprising connections to a plurality of signal circuits, an electronic amplifier associated with each of said signal circuit connections, an oscillograph observation circuit connected with said amplifiers, an electronic commutating circuit for controlling said amplifiers in predetermined sequence to cause the same to subject said observation circuit to the effects of said signal circuits individually in corresponding sequence, an oscillograph time-axis circuit, and an electronic sweep circuit for controlling said time-axis circuit, said sweep circuit comprising a condenser, charging means therefor to give the desired timing action, and a grid-controlled rectier having its cathode connected to said condenser and providing a discharge path for said condenser whereby the same is discharged suddenly when the `voltage of its charge reaches a predetermined value.

20. A cathode ray oscillograph system comprising connections to a plurality of signal circuits, an electronic amplifier associated with each of said signal circuit connections, an oscillograph observation circuit connected with said ampliers, an electronic commutating circuit for controlling said amplifiers in predetermined sequence to cause the same to subject said observation circuit to the effects of said signal circuits individually in corresponding sequence, an oscillograph time-axis circuit, and an electronic sweep circuit for controlling said time-axis circuit, said sweep circuit comprising a condenser and a charging circuit therefor including a pentode of high A. C. plate resistance connected in series with said condenser and serving as a constantcurrent device to give the desired timing action through the charging of said condenser.

2l. A cathode ray oscillograph system: comprising connections to a plurality of signal circuits, an electronic ampliler associated with each of said signal circuit connections, an oscillograph observation circuit connected with said amplifiers, an electronic commutating circuit for controlling said ampliers in predetermined sequence to cause the same to subject said observation circuit to the eects of said signal circuits individually in corresponding sequence, an oscillograph time-axis circuit, an electronic sweep circuit for controlling said time-axis circuit, and

a connection between one of said signal circuit connections and said sweep circuit to synchronize the action of the latter with said signal circuit.

22. A cathode ray oscillograph system comprising connections to a plurality of signal cirlo cuits, an electronic amplifier associated with each of said signal circuit connections. an oscillograph observation circuit connected with said amplifiers, an electronic commutating circuit for controlling said amplifiers in predetermined sequence to cause same to subject said observation circuit to the effects of said signal circuits individually in corresponding sequence; an oscillograph time-axis circuit, an electronic sweep circuit for controlling said time-axis circuit, and a connection between one of said signal circuit connections and said sweep circuit to synchronize the action of the latter with said signal circuit, said connection comprising an electronic coupling device preventing transients set up in the sweep circuit from affecting the signal circuit.

23. A cathode ray oscillograph system comprising connections to a plurality of signal circuits, an electronic ampliiler associated with each of 'said signal circuit connections, an oscillograph observation circuit connected with said ampliers, an electronic commutating circuit for controlling said ampliiiers in predetermined sequence to cause the same to subject said observation circuit to the eects of said signal circuits individually in corresponding sequence, an oscillograph time-axis circuit, an electronic sweep circuitl for controlling said time-axis circuit, a connection from said sweep circuit to said commutating circuit to effect timing of the operation of the latter, and a connection between one of said signal circuit connections and. said sweep circuit to synchronize the action of the latter with said signal circuit.

24. An electrical circuit systemf of the character described, comprising a gaseous rectifier, an alternating current supply circuit therefor, an output circuit having a relatively light load connected thereto, and a resistance connected in series with said supply circuit to insure continuous operation of the rectifier.

25. An electrical circuit system of the character described, comprising a gaseous rectiiier, an alternating current supply circuit therefor, an output circuit having a relatively light load connected thereto, and a variable resistance connected in series with said supply circuit to insure continuous operation of the rectier and to provide a variable output voltage control therefor.

26. The method of controlling a cathode ray oscillograph to cause the same to furnish simultaneous observation of a plurality of signals,

which comprises applying a timing influence to the oscillograph to provide a continuously repeating time axlsfor the observation, and also utilizing said timing influence to subject the oscillograph sequentially to the influence of the different signals in rapid succession.

27. The method ot controlling a cathode ray oscillograph to cause the same to furnish simultaneous observation of a plurality of signals, which comprises applying a timing inuence to the oscillograph to provide a continuously repeating time axis for the observation, and also utilizing said timing iniluence to subject the oscillograph sequentially to the influence of the dierent signals in such manner as to provide individual traces of dlierent signals on each two successive repetitions ot the time axis.

28. The method of visually observing a plurality of signalling indications which comprises developing an electronic ray, deilecting the ray across an observation plane under the influence of timing control signals to provide a continuously repeating time axis of observation in one plane, deilecting the ray in a mutually perpendicular .direction under the inuence of the signalling indications to be observed, cyclically switching the last named deection from one to another of the signalling indications in sequence, and interlocking the switching and timing of the deflection paths to provide representations of diil'erent signalling indications on successive ray traversals along the timing axis path.

29. The method of controlling a cathode ray oscillograph to cause the same tol furnish simultaneous observation of a plurality of signals which comprises applying a timing influence to the oscillograph to provide a continuously repeating time axis for observation and alsoI utilizing said timing influence to subject the oscillograph sequentially to the influence of the diierent signals in such manner as to provide individual traces of each of the different signals of the plurality on each successive repetition of the time axis and then to repeat the representations in the same sequence during the presence of the plurality of signals.

30. A system for visually observing a plurality of signalling indications which comprises means for developing an electronic ray, means for deecting the ray across an observation plane under the influence of timing control signals to provide a continuously repeating time axis of observation in one plane, means for deiiecting the ray in a mutually perpendicular direction under the iniiuence of the signalling indications to be observed, means for switching the lastnamed deflection from one to another of the signalling indications in a predetermined order, and means for interlocking in a predetermined ratio the switching and timing of the deiiection paths to provide representations of different signalling indications for ray traversals along the timing axis path. a

CARL S. ROYS.

HARRY F. MAYER. 

